Abstract
BackgroundGenetic mapping of phenotypic traits generally focuses on a single time point, but biomass accumulates continuously during plant development. Resolution of the temporal dynamics that affect biomass recently became feasible using non-destructive imaging.ResultsWith the aim to identify key genetic factors for vegetative biomass formation from the seedling stage to flowering, we explored growth over time in a diverse collection of two-rowed spring barley accessions. High heritabilities facilitated the temporal analysis of trait relationships and identification of quantitative trait loci (QTL). Biomass QTL tended to persist only a short period during early growth. More persistent QTL were detected around the booting stage. We identified seven major biomass QTL, which together explain 55% of the genetic variance at the seedling stage, and 43% at the booting stage. Three biomass QTL co-located with genes or QTL involved in phenology. The most important locus for biomass was independent from phenology and is located on chromosome 7HL at 141 cM. This locus explained ~20% of the genetic variance, was significant over a long period of time and co-located with HvDIM, a gene involved in brassinosteroid synthesis.ConclusionsBiomass is a dynamic trait and is therefore orchestrated by different QTL during early and late growth stages. Marker-assisted selection for high biomass at booting stage is most effective by also including favorable alleles from seedling biomass QTL. Selection for dynamic QTL may enhance genetic gain for complex traits such as biomass or, in the future, even grain yield.
Highlights
Genetic mapping of phenotypic traits generally focuses on a single time point, but biomass accumulates continuously during plant development
Heritability was high for inflection point (0.82) and Dynamic phenotyping revealed substantial genotype-bytime interactions We observed that image-based digital biomass measurements are a precise proxy for manually measured fresh biomass (Additional file 1 Figure S4), and facilitate plant growth assessments
This study demonstrates the potential of daily trait assessment to uncover the dynamics of trait relationships and to identify quantitative trait loci (QTL) for mapping
Summary
Genetic mapping of phenotypic traits generally focuses on a single time point, but biomass accumulates continuously during plant development. Resolution of the temporal dynamics that affect biomass recently became feasible using non-destructive imaging. Increases in both yield and yield stability are key objectives in plant breeding to support an ever expanding population [1]. Grain yield potential can be improved by enhancing either sink or source strength. Most of the historical increases in barley yield reflect changes in harvest index (weight of grain divided by weight of above-ground biomass), an effect of enhanced sink strength, while overall biomass has remained unchanged [5,6,7]. Other reports suggest a positive relationship between biomass and Neumann et al BMC Plant Biology (2017) 17:137 grain yield [9,10,11] and indicate that increasing biomass may be a promising approach for improving grain yields in barley as it was recently recommended for wheat [12]
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